Solder Fountain System
solder fountain systems have the same basic components. A solder pump and solder
reservoir, various nozzle sizes and controls for solder flow height.
Solder from the reservoir is driven up through the nozzle by the pump.
Nozzles are made of steel with welded seams and connections. It is important
that the nozzle construction allow for the capture of the pump's inflow and for
the runoff of the solder. This prevents the excess solder from splashing and
maintains a usable solder level above the nozzle lip.
Occasionally the opening in the solder fountain table needs to be restricted
to prevent solder splash from contaminating the un-worked part of the board. Do
not close the opening too tight or you may impede the nozzle run off.
Above the solder fountain head there is generally a light projected alignment
mark that permits you to center the part to be removed over the nozzle.
Solder Height Adjustment
Solder height should be set at 1.50 mm -
3.00 mm (.060" - .120") above the lip of the nozzle. The ideal situation is to
have the leads of a component just immersed and wetted without having the wave
exert any upward pressure on the circuit board. The solder fountain table
surface should be parallel to the nozzle surface. Components and leads on the
bottom side of the circuit board may cause the PC board to be uneven, this
condition must be compensated for.
Insufficient immersion will prevent proper heat transfer and reflow. Excess
pressure will cause solder to surge up through holes and to spill out onto the
top side of the circuit board.
Solder Temperature Adjustment
Solder temperature adjustment varies
depending of various factors. Normal setting 260 C (500 F.) During heavy use,
solder temperature may cycle between 250 C - 270 C (480 F - 520 F.) The heaters
should react quickly to normal drops in temperature. The heaters may overshoot
the preset temperature when vigorous activity is suddenly halted. Operators must
be alert to temperature fluctuations that exceed preset standards.
Solder Fountain Time Adjustment
This adjustment can be used to
precisely control operations of a repetitive nature or in instances where you
want to strictly control a circuit board's exposure to the solder fountain heat.
The timer may also be set to maximum and the on/off action of the wave is
controlled by the motor's on/off foot pedal or by lifting the board on and off
There are a variety of removal tools to help extract
the component once reflow has been achieved. The extractor tool should provide
the operator a good grip but should not unduly damage the component during
PC Board Pre-heat
Recommendations for pre-heat range from 1 to 4
hours at 65 C - 120 C ( 150 F - 250 F.) The requirements of temperature and time
for pre-heat depend on the board construction, age and exposure to the
In general terms the pre-heat will serve four purposes.
- To drive out volatiles or moisture from the circuit board. Moisture that has
penetrated the board may cause expansion or delamination when it is rapidly
- To prevent thermal shock to the board. Ambient temperature in buildings in
the winter can be as low as 13 C (55 F.) As the circuit board at this
temperature comes in contact with molten solder, the extreme shock of the widely
varying temperature may cause surface or internal damage.
- Pre-heat may permit you to pre expand the circuit board. Some circuit boards
expand so severely at the point of high heat that they will bow up or down
enough to create difficulties in maintaining proper board profile to the solder
- Pre-heat raises the temperature of the circuit board and the component to be
removed. This allows for quicker component removal. This reduces the potential
for burning of solder mask and the circuit board surface and reduces potential
for other thermal damage.
Procedure - Circuit Board Preparation
The area surrounding the
component to be removed may need protection. If components or the circuit board
surface are susceptible to damage or exposure to solder they may be protected by
using the following procedure:
- Straighten any leads that may prevent the easy removal of the part.
- Apply high temperature tape to any flat surfaces surrounding the rework area to
insulate the surface from extreme temperatures. Or apply high temperature
flexible mask to protect irregular surfaces. The mask may need baking to provide
the proper cure prior to reflow.
- Select an extractor tool and check the fit to be sure the component can be
Procedure - Circuit Board Pre-heat
PC Boards returned from the
field or where they have been exposed to moisture for some time.
- Bake for 4 hours at approximately 75 C (165 F.) Prior to part removal the PC
board should be pre-heated for one hour prior to removal of the part. If
possible perform reflow immediately upon removal of the circuit board from the
oven after completion of the baking cycle. If the circuit board must sit between
the pre-heat and removal, it may sit for the maximum of one night only in a dry
- Top heat during removal is only used when working with the most difficult
components. To apply top heat, a heat gun is positioned directly above the
solder nozzle at a set distance above the circuit board surface. Top heat is
applied for a set time prior to activating the solder fountain. Heat sensitive
chalk applied to the component will signal when the proper temperature has been
Other component temperature
indication techniques can be used.
Procedure - Removal Process
- Turn on the solder fountain system and allow the solder to reach the proper
operating temperature. Clean the machine as needed and test run the pump to be
sure there is no buildup of contamination that may cause a drag on the pumping
- Select the proper nozzle and install it into the solder fountain system. A
nozzle that is too large will expose the circuit board surface to unnecessary
heat. A nozzle that is too small may not reflow all the component leads.
- Check the table height and solder wave height to be sure they are properly
set for the circuit board to be worked on.
- Apply flux to all the leads of the component to be removed. Apply the flux
to both the top and bottom side solder fillets.
- Place the circuit board over the nozzle. Check the position using the
- Activate the solder fountain. Once full solder reflow has been achieved
extract the component with the extractor tool. Operator skill and experience are
required to prevent hole and pad damage caused by premature removal or from heat
damage due to delayed removal.
- Immediately drop the solder fountain to prevent over exposure.
- Allow the circuit board to cool before handling and inspection.
- Clean the area and inspect for signs of damage.